Process of manufacturing products from cornstalks, sugar-cane, sorghum, or analogous pithy stalks and papers produced thereby.



Patented. May 9, 1905.

VIGGO DREVVSEN, OF NEW YORK, N. Y.

PROCESS OF MANUFACTURING PRODUCTS FROM CORNSTALKS, SUGAR-CANE, SORGHUM,OR ANALDGOUS PITHY STALKS AND PAPERS PRODUCED THEREBY.

SPECIFICATION forming part of Letters Patent No. 789,416, dated May 9,1905.

Application filed September 29, 1904. Serial No. 226,446.

To all whom 711; may concern:

Be it known that I, VIeeo Danws EN, a citizen of the Kingdom of Norway,residing in the city of New York, in the county of Kings and State ofNew York, have invented a new and useful Process of ManufacturingProducts from Cornstalks, Sugar-Cane, Sorghum, or Analogous Pithy Stalksand New and Useful Papers Produced Thereby, of which the following is aspecification.

The di'liiculty in preparing fibrous material (cellulose) and otherproducts suitable for the manufacture of paper from these pithy-stalkslies in the different character of the different parts of the stalk. Acornstalk propernamely,withoutleaves or husks, for instanceconsists oftwo parts which can be used by paper manufacturers-to wit, the outsideshell and the pith. The shell has a character similar to wood andcontains a high percentage of fibers, while the pith is spongy andconsists principally of oblong cells. This is also true of thesugar-cane and analogous plants. The shell when treated with chemicalsubstances such caustic soda and sodium sullid, for instance----yields alarge proportion of libers which are adapted for paper-making andproduce an opaque sheet of paper. The pith, on the other hand, whentreated with the same chemical substances disintegrates into cells, and.the sheet of paper derived therefrom is translucent and constitutesparchment-paper. Attempts were made long ago to utilize the stalks inthe manufacture of paper by treatment with a caustic alkali, and incarrying out these attempts various processes were used, the earliest ofwhich consisted in boiling the stalks, after having crushed them, in aweak solution of caustic soda for about six hours. The result was amrchment-like more or less discolored brittle paper which had few uses,and the processes, therefore, never led to any practical manufacturingresult. It was thereafter supposed that the difference in characterbetween the fibers of the shell and the cells of the pith required twoseparate cooking operations wherein the libers of the shell needed astronger solution and a longer time for cooking than were needed for thepith, and it was also thought that if the pith was cooked simultaneouslywith the shell in the same strength of liquor and for the same length oftime as are required for the disintegration of the libers of the shelland their separation from the incrustaceous matter the cells of the pithare practically destroyed and cannot be utilized. In a previousapplication for United States Letters Patent filed by me July 9, 1903,Serial No. 164,759, however, I have described and claimed my discoverythat this is not always the case and that by the use of proper meansonly a single operation of cooking is necessary for the entire stalk,shell, and pith and that both can be used either separately or togetherin making the paper. The papers made by this previous method of minewhile exceedingly useful lacked some q ualities which it was desirableto secure, for the pulp was not sufliciently absorbent and the paperconsequently was not soft enough for the most desirable forms of paperfor printers use and other purposes.

The object of my present invention is to secure these desired results,and l have made the discovery that by following the method hereinafterdescribed the requisite qualities of paper can be produced. Thediscovery is that if the stalks be cooked in a stronger solution and fora longer time than has heretofore been supposed to be possiblewithoutdestroying the utility of the pith I. succeed, instead ofdestroying the pith, in changing its parchment quality to a softabsorbing nature and in getting a superior quality of paper to any whichhas heretofore been produced from these substances, and the markeddifference is illustrated by the fact that if paper heretofore producedfrom these substances is thereafter further cooked according to mydiscovery the quality of the paper will be quite changed, its hardcharacter will be lost, and a paper is produced by this further cookingwhich has the requisite quality of softness.

In carrying out my process I first separate n and cut up the entirestalk into pieces. This exposes the pith lying within the shell. (Thecutting may be omitted,especially where the stalk has been crushed, asin rollers.) 1 then place these pieces of stalk in adigester or rotarycontaining the necessary chemical solutionsay twenty per cent. (20%) ofcaustic soda, (Na2O.H.2O,) calculated from the bonedry weight of thestalk though I do not confine myself to this specific strength of thesolution, for sodium sulfid (NzuS) may be used in admixture with thecaustic soda. Neither do I confine myself to the specific length ofcooking-time and steam-pressure given below so long as the length oftime of cooking, the strength of the cooking liquor, and the steampressure is sufficient to effect the change in the character of thepith-cells as above described. Cooking the stalk for nine hours at asteam-pressure of ninety pounds to the square inch has givensatisfactory results. After cooking the pieces of stalk the pressure isblown off or partially blown off from the digester or rotary, and thecontents are run out into a draining-vat. The dark-colored liquor isallowed to run off and is washed out of the solid material and saved tobe used for special purposes which form no part of this invention. Thesolid washed material, consisting of the cooked fibers and pith-cells,is then thrown on a screen to separate from it any part which may nothave been thoroughly cooked and then can be run directly or afterbleaching or filling or sizing on to the paper machine. This pulp is runout onto the wire of a paper-making machine-for instance,the well-knownFourdrinier machine thence onto the couch-rolls, thence through one ormore presses, and therefrom onto the drying-rolls, and thence onto thecalendering-rolls. By this method I avoid the necessity of using abeating-engine, for the cells are fine enough to replace the beatenfibers of other methods. The paper resulting from this mode of operationis unlike any paper heretofore produced from stalks of the characterdescribed and resembles ordinary opaque soft paper used by printers. Thepaper may, if desired, be sized and likewise filled, as it istechnically termed, with clay, talc, and similar filling material knownin the paper-makers art. The product of this process when the pulp isfilled results in a paper which I have termed imitated coated paper, asthe most appropriate descriptive term, for it is a substitute for coatedpaper. I can, however, make another form of paper by the same process,with an added step which produces writing-paper and also what I havetermed imitation parchment-paper, in that it is unlike theparchment-paper which has heretofore been made from the cooked cells ofthe pith of the stalks of the plants referred to in that while suchformer paper is stiff, brittle, and grease-proof my new paper isflexible, not brittle, and is less grease-proof, while itis translucent.This added step, by

which I produce this new second kind of paper, consists in treating thepulp in a beatingengine, as it is termed in the art, or a similarmachine. In manufacturing this second kind of paper the cooked andwashed fibers and pith-cells, either bleached or unbleached,

instead of being run directly onto the papermachine are conducted to thebeating-engine and beaten therein with watersay for an houruntil thepithcells are broken up. Thereafter the beaten pulp either before orafter sizing is run onto the paper-machine, and the resulting paper hasthe qualities which I have described above.

It is essential to my invention that the cooking liquor must contain acaustic alkali, which is not a salt, but a base, and that the cooking beconducted under a greater pressure than atmospheric pressure and thatthe cooking be conducted for a longer time than has heretofore beenpracticed. Of course some latitude may be allowed to the operator, forif the strength of the cooking liquor be much increased the time ofcooking may be thereby somewhat lessened; but the desirable resultswhich I have obtained will not be realized unless the fibers andpith-cells are cooked substantially longer and in a stronger cookingliquor than has heretofore been thought to be desirable or possible, andthis longer cooking and stronger solution give a totally difl'erentquality of papers from those heretofore produced by former methods,including my own. What I mean by a stronger cooking liquor is one whichcontains from five to ten per cent. of the caustic alkali, calculated tothe weight of water employed. Isecu re amore thorough eradication ofincrustaceous matter and obtain papers, both opaque and translucent,having the characteristics above described.

I do not claim in this application, which I term Case A,the paperswhichI have above described as the imitated coated paper and thetranslucent writing and imitation parchment papers, for I have madethose papers, respectively, the subject-matter of separate applicationswhich I am filing simultaneously herewith designated as Case B ant CaseC, filed September 29, 1904, Serial Nos. 226A L7 and 226A48,respectively; but,

Having thus described my invention, what I claim herein is- 1. Opaque,soft, non-filled paper produced from sugar cane, cornstalks, sorghum andanalogous pithy stalks in which the fibers of the outer shell, thefibers of the vascular bundles and the softened altered and absorbentpith-cells are all intermingled and matted together, substantially'asdescribed.

2. The process of producing opaque, soft, non-filled paper fromsugar-cane, cornstalks, sorghum, and analogous pithy stalks whichconsists in cooking said stalks in a closed vessel under steam-pressurein a cooking liquor containing from fifteen to thirty per cent. ofcaustic soda calculated from the bone-dry weight of the stalk for fromten to four hours according to the strength of liquor employed and undera steam-pressure of from sixty to one hundred pounds, until thepith-cells have been converted into soft absorbent pulp instead ofparchment-like, Water and grease repellent pulp; and then running saidcooked pulp Without beating upon the paper-machine and making papertherefrom, substantially as described.

3. The process of producing opaque, soft, non-filled paper fromsugar-cane, cornstalks, sorghunnand analogous pithy stalks, Whichconsists in first cutting said stalks into pieces; next cooking saidstalks in a closed vessel under steam-pressure in a cooking liquorcontaining from fifteen to thirty per cent. of caus- VIGGO DREWSEN.

Witnesses:

JAMES J. Cosenovm, EDMUND ELLSWORTII FIELD, Jr.

